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The clinical consequences of cholesterol embolisation vary considerably. Patients may be completely asymptomatic when the diagnosis is made coincidentally at renal biopsy or they may present with a distinct clinical syndrome that is associated with a high mortality. As only a minority of patients sustaining cholesterol emboli are recognised clinically, the actual incidence and pathophysiology of the syndrome remains uncertain.
Typical features of the clinical syndrome include livedo reticularis and painful focal digital ischaemia, characteristically with a normal peripheral arterial pulse (the purple toe syndrome). Other clinical features include retinal embolisation, renal failure (usually with baseline renal impairment), labile blood pressure, and abdominal symptoms that may vary depending on which organ is involved.1
Tissue biopsy is the diagnostic investigation of choice. Skin or muscle biopsy can be used but where possible the affected organ should be biopsied. The characteristic pathological lesion is occlusion of affected arterioles by luminal needle shaped cholesterol clefts (fig1). The kidney is the solid organ most commonly affected and renal biopsy is abnormal in approximately 70% of patients with the cholesterol emboli syndrome.1
Making a clinical diagnosis of cholesterol embolisation requires a high index of suspicion as there is no diagnostic serological investigation, and differentiation from a systemic vasculitis can be difficult.2 Abnormalities of routine investigations are generally non-specific, but include an acute phase response (elevated C reactive protein, normochromic normocytic anaemia, and leucocytosis), a transient eosinophilia, thrombocytopenia, reduced complement levels, proteinuria or haematuria or both.
Cholesterol embolisation may be spontaneous or it may occur within eight weeks of arteriography, angioplasty, cardiac surgery or thrombolysis. Elderly male smokers with a history of hypertension and vascular disease appear to be at particular risk. Penetrating mobile semi-occlusive atheroma of the aorta detected by transoesophageal echocardiography has been demonstrated in a number of cases (fig2).3 4 This pattern of atheroma is an unusual finding and it appears to be a marker of severe widespread atheromatous disease. Further studies into the relation between this pattern of atheromatous aortic disease and the cholesterol emboli syndrome are currently in progress.
The outcome of patients with cholesterol embolisation varies considerably. In patients undergoing investigation and treatment for ischaemic heart disease, muscle biopsy has demonstrated cholesterol clefts in 10% of patients.5 None of these patients had any clinical sequelae. In contrast, the clinical syndrome of cholesterol embolisation has a poor prognosis particularly when there is evidence of visceral and renal involvement. Mortality in these patients may approach 80%.1
Conventional treatment is supportive with aggressive blood pressure control and, if necessary, renal replacement treatment. There is no evidence that steroids1 or anticoagulation6are beneficial. Some centres have advocated arterial surgery for atheroembolic disease, however, there are no randomised comparisons of surgery with medical treatment. In patients who are gravely ill, the extent of the vascular disease and the presence of multiorgan involvement makes any proposed surgical intervention extremely high risk. Conclusions The incidence of cholesterol embolisation is probably underestimated as it may be clinically silent. When the clinical syndrome does occur, it is difficult to diagnose. Patients with diffuse vascular disease who have undergone a recent vascular intervention are at particular risk. An increased awareness of the diagnosis and further research into the pathophysiological mechanisms underlying cholesterol embolisation are necessary to improve understanding and reduce patient mortality.